Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
Manual power levels with an Auto Flash
Posted By: Class A, 11-26-2009, 09:39 PM

Auto flashes are handy when used on their own. They use a thyristor to shut off the flash once the exposure has been deemed sufficient by the flash.

When using multiple flashes in conjunction, however, it is best to set their power levels manually, i.e., not let the flash decide which output level to use.

Many Auto flashes do not allow the setting of the power level but here's a trick to get at least one manual level:

If one blinds the photo diode with which the flash measures the exposure (say with a opaque tape), the flash will always go full power with respect to a particular setting. Depending on the level chosen, this will result in a consistent flash output, corresponding to a manual power setting.

The Vivitar 2500 has four settings:
  • M (manual) = full power
  • blue (auto setting 1) = up to full power
  • red (auto setting 2) = up to ~1/3 power
  • triangle (autowinder mode) = 1/8 power
So with this flash one can achieve three output levels: full, ~1/3 (requires blinding of the photo diode), and 1/8.

I suspect that one of the auto setting of an auto flash will always go up to full power. I wouldn't make sense if the flash weren't trying to give "its best".

P.S.: When using older flashes, always make sure that their trigger voltage is not too high when using them on-camera.

Last edited by Class A; 11-30-2009 at 02:41 AM.
Views: 5,991
11-27-2009, 12:29 PM   #2
New Member
stu49's Avatar

Join Date: Oct 2009
Location: Norfolk, England
Posts: 19
You can also cover the sensor with sticky paper circles to up the power output (more circles, more power) ;-) handy if the flash only has 1 auto mode.

  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
auto, exposure, flash, flashes, level, levels, output, power, power levels
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Manual power levels with an Auto Flash Class A Flashes, Lighting, and Studio 1 11-26-2009 09:57 PM
Auto power shut down on the AF 360FGZ Russell-Evans Pentax Camera and Field Accessories 4 06-26-2009 01:05 AM
For Sale - Sold: Multiple Auto (Digital & Film) and Manual Lenses, flash + more jjdgti Sold Items 18 10-03-2008 09:30 AM
540FGZ & auto power off Groundloop Pentax Camera and Field Accessories 4 05-28-2008 11:29 PM
Optio W10 and Auto-Levels betsypdx Pentax Compact Cameras 0 08-29-2007 11:06 PM

All times are GMT -7. The time now is 11:18 AM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]